Method for cleaning producer gas using a microwave induced plasma cleaning device

ABSTRACT

A device and method for cleaning producer gas includes a filter bed chamber, a microwave chamber, a first catalytic chamber and a second catalytic chamber. The filter bed chamber comprises an inlet for carbon-based material and a spent carbon outlet. The microwave chamber comprises a permeable top and wave guides around the perimeter through which microwaves can be introduced into the device using magnetrons. The first catalytic chamber is connected to the microwave chamber, and the second catalytic chamber is connected to the first catalytic chamber. The method comprises using the device by filling the filter bed chamber with carbon-based material, introducing microwaves into the microwave chamber using the magnetrons and wave guides, dissociating heavy carbons entrained within the gas by passing the gas through carbon-based material in the filter bed chamber, the microwave chamber, the first catalytic chamber and the second catalytic chamber.

RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 14/517,629, filed Oct. 17, 2014, and it claims priority fromU.S. Provisional Patent Application No. 62/006,448, filed Jun. 2, 2014,the contents of which are both incorporated herein by reference.

BACKGROUND OF THE INVENTION

Gasification is a continuous thermal decomposition process in whichsolid organic or carbonaceous materials (feedstock) break down into acombustible gas mixture. The combustible gas components formed areprimarily carbon monoxide (CO), hydrogen (H2), and methane (CH4). Othernon-combustible gases such as nitrogen (N2), steam (H2O), and carbondioxide (CO2) are also present in various quantities. The process ofgasification involves pyrolysis followed by partial oxidation, which iscontrolled by injecting air or other oxygen containing gases into thepartially pyrolysed feedstock. More specifically, biomass gasificationis a sequence of reactions including water evaporation, lignindecomposition, cellulosic deflagration and carbon reduction. Ifconcentrated oxygen is used, the resulting gas mixture is called syngas.If air (which includes nitrogen) is used as the oxidant, the resultinggas mixture is called producer gas. For simplicity, the term “producergas” as used herein shall include both syngas and producer gas. Both gasmixtures are considered a “fuel gas” and can be used as a replacementfor natural gas in many processes. They can also be used as a precursorto generate various industrial chemicals and motor fuels. When biomassis used as the feedstock, gasification and combustion of the producergas is considered to be a source of renewable energy.

Producer gas may be burned directly in some engines and burners,purified to produce methanol and hydrogen, or converted via theFischer-Tropsch and other methods and processes into synthetic liquidfuel.

Charcoal has been used to clean liquids and gases since as early as2000-1500 B.C. As gas passes through activated carbon, the carbonabsorbs many of the impurities as well as CO and CO2.

Microwaves have been used to heat substrates since the 1950s, withadoption of microwaves to catalyze chemical reactions beginning in the1980s. Microwaves have the ability to heat a substrate without heatingthe surrounding vessel and also the ability to heat the inside of asubstrate rather than simply heating the outside of it. Microwaves canalso heat a substrate faster than traditional heating methods. Finally,it typically requires less energy to heat a substrate using a microwavethan through conduction or convection.

Many devices and techniques have been used to purify, clean and preparefuel gases, particularly syngas created as a result of gasification ofbiomass in the presence of concentrated oxygen and producer gas createdas a result of gasification of biomass in the presence of air (whichincludes Nitrogen). In order for syngas or producer gas to be useful asa fuel gas, the tar and other contaminants must be removed from the gas.

Current devices and methods typically rely on partially combusting theunprocessed gas in order to generate the energy required to break downtars. These devices and methods waste the gas and may introduceadditional contaminants as a result of incomplete combustion of tars.

What is needed is an efficient, low cost device and method to removetars and other contaminants from unprocessed syngas and producer gas inorder to prepare fuel gas. The device and method should not rely oncombusting the gas as an energy source, but should rely on a lower costenergy source to complete the purification.

SUMMARY OF INVENTION

Disclosed is a device and method for cleaning producer gas usingmicrowaves, activated carbon and proprietary microwave absorbers thatproduce heat for thermal cracking of tars and long chain hydrocarbons toyield higher ratios of pure gas than are currently attained usingtraditional techniques. When microwaves are focused on a chamber of suchunprocessed gas, the gas heats, and the carbon microwave interactionionizes to a plasma, the combination of processes causes impurities andheavy carbons to dissociate within the gas stream. By passing the gasthrough a bed of activated carbon (for example, biochar recovered from adowndraft gasifier) or lignite before it is microwaved, many of theimpurities can be physically captured by the activated carbon andseparated from the gas. The combination of carbon filtration and plasmaionization cleans the gas and yields a higher ratio of clean pure gasfor applications requiring that quality.

These and other advantages of the invention will be further understoodand appreciated by those skilled in the art by reference to thefollowing written specifications, claims and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of the device;

FIG. 2 is a side cutaway view of the device, including a feed augerassembly;

FIG. 3 is a side cutaway view of the device, including a residueextraction auger; and

FIG. 4 is a top view of the device.

DETAILED DESCRIPTION

It is to be understood that the specific devices and processesillustrated in the attached drawings, and described in the followingspecification are exemplary embodiments of the inventive conceptsdefined in the appended claims. Hence, specific dimensions and otherphysical characteristics relating to the embodiments disclosed hereinare not to be considered as limiting, unless the claims expressly stateotherwise. The gas cleaning device and it features are listed here, andmore details of embodiment options are discussed below.

I. Device Overview

The device 100 is a standalone gas cleaning unit that accepts anunprocessed stream of gas, filters the gas through a bed of activatedcarbon and then ionizes the gas stream as well as exposing it to hightemperatures by directing microwaves into it. The purified or processedgas is siphoned off so that it may be cooled and used in industrial andcommercial applications.

As shown in FIGS. 1, 2, and 3, the device 100 can be configured in manyways. In one embodiment, the device comprises the following components:a feed auger assembly 110; a filter bed housing 120; a microwave chamber200; at least one gas inlet 330; a residue extraction auger assembly130; and at least one catalytic chamber. As shown in FIG. 1, the devicecan be constructed as a first vertically positioned tube, the tubehaving a perimeter, an external wall 121 and a proximal end 124 and adistal end 123. As shown in FIG. 2, the device has an interior wall 122and a first catalytic chamber 240. As shown in FIG. 3, a secondcatalytic chamber 380 comprises a second vertically positioned tube, thesecond tube also having a perimeter, an external wall 381, a proximalend 384 and a distal end 383. As shown in FIG. 3, the second catalyticchamber 380 can also have an interior wall 385.

As shown in FIG. 1, the first vertically positioned tube can beconstructed with several shorter vertically positioned tubes of the samediameter bolted together. In one embodiment, each vertically positionedtube is between about 48 inches long and 60 inches long, for a totalcombined tube length of about 228 inches. In one embodiment, the firstvertically positioned tube is made from A36 steel plates. In oneembodiment, the diameter between opposing interior walls of the firstvertically positioned tube is approximately 26 inches.

As shown in FIG. 2, in one embodiment, the device 100 is housed in afirst vertically positioned tube having a perimeter, an interior wall,an exterior wall 121, a proximal end 124 and a distal end 123. In oneembodiment, the housing contains a filter bed chamber 220 at theproximal end 124; an inlet 201 for carbon-based material and a spentcarbon outlet 250; a gas inlet 330 located between the spent carbonoutlet 250 and the filter bed chamber 220. The housing contains amicrowave chamber 200 located above the filter bed chamber 220. Themicrowave chamber 200 has a permeable top 202 comprising a microwaveabsorbing material, wave guides 150 located around the perimeter throughwhich microwaves can be introduced into the device 100, and a magnetronand an isolator attached to each wave guide 150. The device 100 can havea first catalytic chamber 240 connected and distal to the microwavechamber 200; a gas outlet 331 connected to the first catalytic chamber240; and, in one embodiment, a second catalytic chamber 380 connected tothe gas outlet 331 of the first catalytic chamber 240. The secondcatalytic chamber 380 can be a second vertically positioned tube havinga perimeter, an interior wall 385, an exterior wall 381, a proximal end383 and a distal end 384.

The method of cleaning gas involves using the device described in theprevious paragraph by performing the following steps: filling the filterbed chamber 220 up to the top of the filter bed chamber 220 withcarbon-based material; introducing microwaves into the microwave chamber200 using the magnetrons and wave guides 150; dissociating heavy carbonsentrained within the gas by passing gas through the gas inlet 330, thecarbon-based material in the filter bed chamber 220, the microwavechamber 200, the first catalytic chamber 240 and the second catalyticchamber 380; and then siphoning the purified gas.

II. Microwave Chamber Assembly

A. Feed Auger Assembly

In one embodiment, the biochar (also called activated carbon) can be theby-product of downdraft gasification, coal or any other carbon-basedmaterial suitable for filtration. As shown in FIG. 2, the activatedcarbon enters the device 100 through an auger chute 210, the auger chute210 has an inlet 214 and an outlet 215. The device 100 has a filter bedchamber inlet 201 for activated carbon to enter a filter bed chamber220. In one embodiment, the auger chute 210 feeds carbon-based material,such as, for example, biochar into the top of the filter bed chamber220, adding to the bed of carbon-based material within the chamber. Thefeed auger assembly 110 can extend all or part of the way to the filterbed chamber inlet 201. Microwaves can be prevented from back-flowingthrough the auger chute 210 by the carbon-based material itself, whichinteracts with the microwaves at the outlet of the auger chute 210 or bya guide if the guide extends into the microwave chamber 200.

B. Filter Bed Chamber

In one embodiment, the biochar can fill the device 100 up to themicrowave chamber 200. In this embodiment, the biochar bed forms thebottom of the microwave chamber 200. In operation, the leading edge ofthe biochar is an interface that acts as a catalyst during operation ofthe device for creation of a plasma field due to the interaction of themicrowaves with the biochar.

The device's 100 control systems determine when to initiate each biocharfill cycle based on the signals, such as temperature or pressurechanges, received from various sensors and indicators on the device 100.The biochar level can be maintained by a radio-wave proximity switch.The end user may also automate the gasifier feedstock filling processwith a timer or by using a microwave sensor or another suitable filllevel indicator to detect the presence of feedstock at the fill level inthe gasifier. The device 100 may have one or more fill level indicatorscapable of functioning in high temperature environments. The fill levelindicator can be any indicator that will not interfere with or sufferfrom interference from the microwaves in the device 100. In oneembodiment, once the fill level indicator detects that the biochar levelis low, feed auger assembly 110 begins to feed biochar into the filterbed chamber inlet 201. One device design with multiple fill levelindicators allows more options in choosing the height of the biocharresidue bed when using an automatic filling system. The feed augerassembly 110 can be pressurized to match the pressure of the filter bedchamber 220. In one embodiment, the activated carbon is fed into thefilter bed chamber 220 through the filter bed chamber inlet 201, thefilter bed chamber inlet 201 being located in the upper half of thefilter bed chamber 220.

C. Microwave Chamber

The microwave chamber 200 can be optimized in shape and materials usedto generate the heat required for purification of the unprocessed gas.As shown in FIG. 2, the geometry of the microwave chamber 200 can be acylindrical tube having walls and a top 202 and a bottom 203. The bottom203 of the microwave chamber 200 can connect to another tube that is afilter bed chamber 220, also having a top 223 and a bottom 224. In oneembodiment, the microwave chamber 200 and the filter bed chamber 220 area single tube. In another embodiment, the tube is a non-cylindrical tubesuch as a square or a rectangle.

Above the bed of biochar there is a microwave chamber 200, the size ofwhich microwave chamber 200 can vary. The microwave chamber 200 can be atube or a conical shaped chamber. The microwave chamber 200 is designedto concentrate microwave fields created by electronically controlledmicrowave guns (also called magnetrons) located around the perimeter ofthe outside microwave chamber 200. The walls of the microwave chamber200 are designed so that microwaves penetrate the walls at particularlocations. The microwave chamber 200 can have holes or indentations toaccommodate microwaves to pass through the walls. The design of themicrowave chamber 200 allows the concentration of the microwaves tooccur with discharges occurring between particles of biochar. Theconcentrated effect of these discharges will form a plasma regioncausing temperatures within the plasma regions to reach just under atheoretical temperature of 5,000 degrees F. In one embodiment, the top202 of the microwave chamber 200 is made up of a specially designedlining such as silica carbide and aluminum oxide a carbon and aluminumoxide mixture. In one embodiment, the interior of the entire device 100is lined with silica carbide, silica oxide, aluminum oxide, refractoryalloys, other ceramics or another material having similar propertiesthat is stable at high temperatures. In one embodiment, certain areas ofthe microwave chamber 200 are lined with a microwave absorbing material260 that will produce high temperature zones to further enhance thethermal cracking process. The combination of materials used throughoutthe microwave chamber 200 also prevents microwaves from escaping thedevice 100. The microwave absorbing material can be any material thateffectively converts microwave energy into heat energy. These materialscan be, for example, without limitation, silica carbide mixes(concentrations of between 2.5% and as high as 12% suspended in anystandard high temperature ceramic slurry).

The cellular wall structures of biochar or lignite have the geometriesthat are necessary for a discharge. The device 100 creates and sustainsa plasmoid in a confined environment, the “e-field” density at the topof the bed of biochar promotes a plasma discharge. The top of the bed ofbiochar is at or near the top 223 of the filter bed chamber 220. Theplasma discharge is a manifestation of the densified e-field interactingwith the biochar. The continued supply of the microwaves and replacementof the biochar sustains the discharge within the environment. Thebiochar has sharp points along its surface, which promote the creationof a discharge. The interaction between the electromagnetic wave andthese points causes the plasma discharge. Unlike other materials, thegeometry of biochar promotes discharges at fairly low power levels. Therange of power levels required for a discharge from biochar is lowerthan what is required for materials such as biomass.

As shown in FIGS. 1 and 4, in one embodiment, microwaves can beintroduced into the microwave chamber 200 using magnetrons 151 throughapproximately seven wave guides 150 located at holes or indentationsaround the circumference (or perimeter) of the microwave chamber 200.Each wave guide 150 is non-opposed relative to the others and can bepositioned on different vertical planes so that no wave guide outletpoints to any other wave guide 150. In one embodiment, the power of eachmagnetron 151 can be between 1.5 kW and 5 kW. The wave guides can bestandard 1.7 inch×3.4 inch wave guides with a WR340 flange. Themagnetrons 151 can be fired by programmable logic controlled powersupplies. They can all fire at 2.45 GHz (standard class D emitters). Thewave guides 150 can be straight and capped. The microwaves can passthrough the caps, which caps can be made of ceramic material. The waveguides 150 can also use tuners. The tuners can also be omitted if theemitters used in an embodiment inherently reduce back-scatter. However,an isolator can be attached in some embodiments to protect the magnetron151 and increase the equipment life (prevent overheating from reflectedmicrowaves). For example, in one embodiment, there is an isolator 152between the magnetron 151 and the wave guide 150. The wave guides 150can guide a specific wave frequency, which frequency is dictated by themagnetron manufacturer. The frequency can change according to theembodiment of the device. The wave guides 150 guide the microwaves tothe microwave chamber 200. The power settings can be set by cycling themagnetron power supplies. These can be an inverter type/style powersupply. The microwave frequency can be different on some embodimentsbased on the magnetron selected. In one embodiment, the device isdesigned to get as much microwave energy into the plasma area (bottom ofthe microwave chamber) as possible at a reasonable cost. This costfactor not only relates to the efficiency of the magnetron but also theinitial cost for the hardware. Lower frequency microwaves penetrate theresidue bed better while higher frequencies will skim the surface andincrease the specific temperature of the contact area more effectively.Either range of frequencies can be effective.

The heat from the microwaves in the microwave chamber 200 at the e-fieldcauses the biochar to partially oxidize and smolder in the filter bedchamber 220. The biochar generates heat which otherwise would have hadto be created.

The device 100 is designed to spread the discharges across the entirearea of the microwave chamber 200 by containing the microwaves into acontrolled zone, and using barriers to contain them. The design of themicrowave chamber 200 (such as its geometry) also optimizes theinteraction of the incoming gas, incoming microwaves, incomingsubstrate, exiting gas, and exiting substrate to optimize theinteractions between the e-field, gas, and biochar. The microwavechamber 200 has a ceiling or top, and the ceiling or top can be linedwith tiles. The tiles can contain a catalyst impregnated ceramic thatconverts microwave energy into heat energy. This ceramic barrier isprimarily for microwave containment but also serves as a final “zone”(catalytic chamber shown in FIG. 2 as 240) at which tars can be brokendown (by a standard thermal mechanism) as gas passes out of themicrowave chamber 200 into a catalyst chamber.

D. Gas Inlet Ports

As shown in FIGS. 2 and 3, in one embodiment, the device 100 comprisesgas inlet ports 330 for gas to enter and a microwave chamber inlet 201for activated carbon to enter the microwave chamber 200. In oneembodiment, the gas is introduced through flanged nozzles ⅓^(rd) way upfrom the bottom of device 100. In another embodiment, the gas isintroduced through inlet ports 330 at the bottom of the filter bedhousing 120. Each inlet 330 can be equipped with di-opposed twin nozzlesand a deflecting diffuser above each nozzle entry point.

E. Residue Extraction Auger Assembly

The microwave chamber 200 or, in one embodiment, the filter bed chamber220 further comprises an outlet 250 for spent carbon to exit themicrowave chamber 200. The outlet 250 can be attached to a residueextraction assembly 130, having a residue extraction auger 361 and valveassembly 362. In one embodiment, the residue extraction assembly is anauger and pocket valve.

The residue extraction auger 361 may be made of steel, stainless steelor another strong, thermally stable, non-porous material. Biochar exitsthe device 100 by way of the residue extraction auger 361. The residueextraction auger 361 can be arranged at or near the bottom of the device100. In one embodiment, at least two residue extraction augers 361 aresymmetrically arranged with respect to center axis of the device 100.

The residue extraction auger 361 can be a tube-style auger. The residueextraction auger 361 can move the biochar into a pocket valve 362 thatis bolted to the end of a cross pipe spool, which is bolted to theresidue extraction auger 361. In one embodiment, the pocket valve 362 isa standard, air-actuated 8-inch or 10-inch ball valve where the ball issealed on one end. When in the “up” position, the ball forms a bucket.The residue extraction auger 361 can be controlled by the device'scontrol system so that while the pocket valve 362 is in the up position,the residue extraction auger 361 deposits biochar into the pocket valve362. When the control system stops this process, the residue extractionauger 361 stops and the pocket valve 362 rotates to the “down” position,dumping its contents into an external collection bin or some othersecondary removal system. Because the ball on the pocket valve 362 isclosed on one end, the pocket valve 362 remains sealed at all times andprevents producer gas from leaking out of the residue extractionassembly 130. A small amount of producer gas does escape, but can bevented safely by a high-point vent pipe or drawn out by vacuum pump.

The device 100 can maintain an appropriate activated carbon level in thefilter bed chamber 220 by controlling the rate at which activated carbonis added and the spent carbon is removed from the device 100. In oneembodiment, the device 100 has a residue extraction system that monitorsthe level of carbon in the device using a fill level indicator.

As biochar is consumed, it is replaced by additional biochar. This isaccomplished by the feed auger assembly 110, which adds additionalbiochar to the device 100 and by the residue extraction assembly 130which removes spent biochar from the device 100. The device 100 may beautomated to continuously add biochar to the filter bed chamber 220based on measurements taken by a fill level sensor 290 that detects whenthe level of biochar gets low.

In one embodiment, the device can have a water jacket 370. As a resultof the water jacket 370 the amount of insulation can vary by a largemargin and because of this, the total diameter of the device itself. Inone embodiment, the device can have features to protect the operatorfrom hot surface areas and stray microwaves, such as, withoutlimitation, an aluminum safety cage or perforated steel cage, similar tothe screen found in the door of a consumer microwave at home. Straymicrowaves scatter effectively in water, and a water jacket 370 is alsoan excellent means of keeping the reactor tubes cool.

IV. Catalytic Chamber(s)

As shown in FIG. 2, in one embodiment, a first catalytic chamber 240 isabove the microwave chamber 200. In one embodiment, as shown in FIG. 2,this first catalytic chamber 240 can be cube-shaped and form the top 202of the microwave chamber 200. As discussed above, this final “zone” orfirst catalytic chamber 240 can form a ceiling or top 202 to themicrowave chamber 200, which can be lined with tiles. The tiles cancontain a catalyst impregnated ceramic that converts microwave energyinto heat energy. As shown in FIG. 2, the tiles can be arrangedvertically, parallel with respect to one another, which forms apermeable barrier and allows gas to pass into the first catalyticchamber 240. In another embodiment, the at least one catalytic reactionchamber is adjacent to the microwave chamber 200.

In one embodiment, an additional reaction chamber is a second catalyticchamber 380. In one embodiment, the second catalytic chamber 380 isadjacent to the microwave chamber 200. As shown in FIG. 1, the secondcatalytic chamber is contained within a housing 180. As shown in FIG. 3,the second catalytic chamber 380 has an exterior wall 381, an interiorwall 385, a proximal end 383 and a distal end 384. The distal end 384can comprise a first pebble bed 386. The proximal end 383 can comprise asecond pebble bed 388. Between the first pebble bed 386 and the secondpebble bed 388 is a second wave guide section 389.

These catalytic chambers can contain a variety of catalysts, such asaluminum oxide that are designed to accelerate gas cleaning and biocharreduction. Injection of steam or purified oxygen can also be introducedto increase gas quality as well.

The device 100 further comprises a gas outlet 331. In one embodiment,the gas outlet 331 is on the top of the microwave chamber 200 and inanother it is on top of the first catalytic chamber 240. In anembodiment with a second catalytic chamber 380, the second catalyticchamber 380 and the microwave chamber 200 (or, as shown in FIG. 3, thefirst catalytic chamber 240) can be connected by a flanged pipe 390.

V. Gas Flow

In one embodiment, gas enters at the bottom of the filter bed chamber220 and passes upward through bed of biochar into the microwave inducedplasma in the microwave chamber 200. As the gas travels through thebiochar, the biochar absorbs CO, CO2, water and other impurities. Uponexiting the biochar, the gas then passes through the e field and theplasmoid where most, if not all, of the remaining carbon materials,including tars, entrained in the gas are dissociated. While the biocharor lignite is discharging, the gas moves through the microwave chamber200 by pressure differential, but continues to be irradiated withmicrowaves. The gas then passes to the heated top 202 of the microwavechamber 200.

The energy level of the electrons in the heated gas molecules is alreadyelevated enough to favor the creation of plasma. A cold gas wouldrequire much more energy to produce the same effect.

The plasma field will naturally stay away from the walls of the device.In one embodiment, steam is injected at a point just below the plasmaregion near the bottom of the “lip” (not shown) that supports theimpregnated catalyst disks/tiles. The steam cools the lip and the silicacarbide. The hypotheses is that a small enough amount of steam would notaffect the plasma state but will in fact liberate some Hydrogen.

In one embodiment, there is a thermocouple on or near the gas outlet331. There are several different redundant control methods used in thedevice 100, and most function as a means by which more precise controlcan be achieved throughout the process. In one embodiment, an effectivecontrol method is to monitor the temperature of various parts of thedevice 100. These temperatures are obtained by way of embeddedthermocouples inside of the lined wall of the device 100. In oneembodiment, the device's 100 control system uses this information tochange the level of microwaves or speed of biochar injection andremoval.

One embodiment improves the consistency of the temperature by lining theentire device 100 with silica carbide, silica oxide, aluminum oxide,refractory alloy, other ceramics or another material that is stable athigh temperatures. This lining helps to evenly distribute and conductheat across the device 100 and allows the use of thermocouples whileprotecting them from the reactions occurring inside the device 100.

The control system may use all of the different methods and combine saidmethods into an algorithmic controller. The latter does not only allowfor redundancy throughout the control system, but also ensures muchgreater reliability and efficiency. It furthermore ensures that theproducer gas is of constant and high quality.

VI. Device Control System

Optimizing the device's 100 operation requires precise real-timeadjustments to control the location of the plasmoid. For example, if amechanical device were inserted in the plasmoid to adjust its location,the high temperatures (between 1600 F and 5000 F) in the microwavechamber 200 would destroy the mechanical device. Therefore, a residueextraction auger is used to control the removal of biochar from thedevice as it can be placed below the much cooler filter bed of biochar.The changes to the height of the biochar bed, caused by increasing therate of removal of biochar from the device, induce some of the necessarychanges to adjust the vertical location of the plasmoid.

Several methods and systems may be used as part of the overall devicecontrol system to induce changes to and to control the plasmoid whilethe device 100 is operational. The control system uses variousalgorithms to monitor and adjust the device. The control system mayinclude subsystems capable of real-time adjustments and account forother methods that may only be adjusted while the device is offline.

VII. Sensors and Components

In one embodiment, the control system requires sensors locatedthroughout the device to monitor the device. In one embodiment, thedevice 100 has a temperature sensor at one or more of the following: (1)biochar outlet 250; (2) gas inlets 350; (3) mid-point of the filter bedchamber 220; (4) the gas outlet 331; and (5) the filter bed chamberinlet 201. In one embodiment, the device 100 has pressure sensors at:gas inlet 330; and gas outlet 331. In one embodiment, the device 100 hasa fill level sensor at: a radio-wave proximity switch and a biocharstorage tank level switch. In one embodiment, the device 100 hasvariable frequency drives operating the fee auger assembly 110 and theresidue extraction assembly 130. In one embodiment, the device 100 hasvalving at: the feed auger assembly 110 and the residue extractionassembly 130.

Interpretation:

Embodiments of this invention are described herein. Variations of thoseembodiments may become apparent to those having ordinary skill in theart upon reading the foregoing description. The inventors expect thatskilled artisans will employ such variations as appropriate, and theinventors intend for the invention to be practiced other than asspecifically described herein. Accordingly, this invention includes allmodifications and equivalents of the subject matter recited in theclaims appended hereto as permitted by applicable law. Moreover, anycombination of the above-described elements in all possible variationshereof is encompassed by the invention unless otherwise indicated hereinor otherwise clearly contradicted by context.

While the disclosure above sets forth the principles of the presentinvention, with the examples given for illustration only, one shouldrealize that the use of the present invention includes all usualvariations, adaptations and/or modifications. within the scope of theclaims attached as well as equivalents thereof.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing an invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., “including, but notlimited to,”) unless otherwise noted. Recitation of ranges as valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it was individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention (i.e.,“such as, but not limited to,”) unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

Those skilled in the art will appreciate from the foregoing that variousadaptations and modifications of the just described embodiments can beconfigured without departing from the scope and spirit of the invention.Therefore, it is to be understood that, within the scope of the appendedclaims, the invention may be practiced other than as specificallydescribed herein.

What is claimed is:
 1. A method of cleaning gas which uses a gascleaning device, said device comprising: a first vertically positionedtube having a perimeter, an interior wall, an exterior wall, a proximalend and a distal end, comprising: a filter bed chamber located at theproximal end of the first vertically positioned tube, said filter bedchamber having a top and a bottom, said top of the filter bed chamberhaving an inlet for carbon-based material and said bottom having a spentcarbon outlet and a gas inlet; a microwave chamber comprising: a gaspermeable top comprising a microwave absorbing material, wherein the gaspermeable top is a first catalytic chamber, a perimeter, a bottomconnected to the top of the filter bed chamber, wave guides locatedaround the perimeter through which microwaves can be introduced into themicrowave chamber, and a magnetron and an isolator attached to each waveguide; a gas outlet located at the distal end of the first verticallypositioned tube and connected to the first catalytic chamber; and asecond catalytic chamber connected to the first catalytic chamber, saidsecond catalytic chamber comprising a second vertically positioned tubehaving a perimeter, an interior wall, an exterior wall, a proximal endand a distal end; said method comprising: filling the filter bed chamberup to the top of the filter bed chamber with carbon-based material;introducing microwaves into the microwave chamber using the magnetronsand wave guides; dissociating long chain hydrocarbons entrained withinthe gas by passing gas through the gas inlet, the carbon-based materialin the filter bed chamber, the microwave chamber, the first catalyticchamber and the second catalytic chamber; and siphoning the purifiedgas.
 2. The method of claim 1, further comprising filling the filter bedchamber using a feed auger assembly connected to the filter bed chamber.3. The method of claim 2, further comprising removing spent carbon usinga residue extraction auger assembly attached to the spent carbon outlet.4. The method of claim 1, further comprising concentrating a microwavefield within the device using microwaves supplied by magnetrons.
 5. Themethod of claim 3, further comprising maintaining levels of carbon-basedmaterial using the residue extraction auger assembly attached to thespent carbon outlet.
 6. The method of claim 2, further comprisingrefilling and maintaining levels of carbon-based material using the feedauger assembly connected to the filter bed chamber.
 7. The method ofclaim 6, further comprising monitoring and adjusting levels ofcarbon-based materials using a control system and sensors.
 8. The methodof claim 1, wherein the microwave absorbing material comprises ceramictiles impregnated with a material that catalyzes conversion of microwaveenergy into heat energy.
 9. The method of claim 1, said device furthercomprising a lining on the interior wall wherein the lining is silicacarbide and aluminum oxide or carbon and aluminum oxide.
 10. The methodof claim 1, further comprising injecting steam or purified oxygen intothe second catalytic chamber.
 11. The method of claim 1, wherein eachwave guide of said device is on a different vertical plane.
 12. Themethod of claim 1, said device further comprising a water jacket aroundthe device.
 13. The method of claim 1, wherein the carbon-based materialis activated carbon.